Vehicle

ABSTRACT

A vehicle includes at least three wheels including a steered wheel, at least one drive source to drive at least two of the wheels, and a front suspension including an upper arm and a lower arm supporting the steered wheel. In a state where the vehicle is stationary on a level road surface, an anhedral angle of the lower arm is larger than an anhedral angle of the upper arm, and a difference between the anhedral angle of the lower arm and the anhedral angle of the upper arm is 5 degrees or more.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of PCT Application No.PCT/JP2021/014361 filed on Apr. 2, 2021. The entire contents of thisapplication are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a vehicle.

2. Description of the Related Art

A handle-type electric wheelchair has been known as one of the vehiclesthat run with a human on board (e.g., Japanese Laid-Open PatentPublication No. 2000-247155). A handle-type electric wheelchair issometimes referred to as an electric cart.

Generally, handle-type electric wheelchairs are used for traveling onrelatively flat paved roads. For example, the user can ride ahandle-type electric wheelchair between home and a store to do shopping.

SUMMARY OF THE INVENTION

There is a need to further improve the driving performance of suchvehicles.

A vehicle according to a preferred embodiment of the present inventionincludes at least three wheels including a steered wheel, at least onedrive source to drive at least two of the wheels, and a suspensionincluding an upper arm and a lower arm supporting the steered wheel,wherein, in a state where the vehicle is stationary on a level roadsurface, an anhedral angle of the lower arm is larger than an anhedralangle of the upper arm, and a difference between the anhedral angle ofthe lower arm and the anhedral angle of the upper arm is 5 degrees ormore.

As a result of the anhedral angle of the lower arm being larger than theanhedral angle of the upper arm, with the anhedral angle differencebeing 5 degrees or more, it is possible to reduce the amount of changein the angle between the longitudinal direction of each of the upper armand the lower arm and a tire center line when the suspension moves in astroke. This increases a clearance between the suspension and thesteered wheel, and it is possible to both increase the wheel stroke andincrease the steering angle of the steered wheel.

In a preferred embodiment, the difference between the anhedral angle ofthe lower arm and the anhedral angle of the upper arm may be 5 degreesor more and 9 degrees or less.

As a result of the difference between the anhedral angle of the lowerarm and the anhedral angle of the upper arm being large, it is possibleto reduce the amount of change in the angle between the longitudinaldirection of each of the upper arm and the lower arm and the tire centerline when the suspension moves in a stroke.

In a preferred embodiment, the amount of change in a camber angle of thesteered wheel relative to the wheel stroke of the suspension may be 5degrees or more.

As a result of the camber angle of the steered wheel being able tosignificantly change in response to the stroke of the suspension, it ispossible to reduce the amount of change in the angle between thelongitudinal direction of each of the upper arm and the lower arm andthe tire center line.

In a preferred embodiment, the amount of change in the camber angle ofthe steered wheel relative to the wheel stroke of the suspension may be5 degrees or more and 10 degrees or less.

As a result of the camber angle of the steered wheel being able tosignificantly change in response to the stroke of the suspension, it ispossible to reduce the amount of change in the angle between thelongitudinal direction of each of the upper arm and the lower arm andthe tire center line.

In a preferred embodiment, when the suspension moves in a bound stroke,the camber angle of the steered wheel may have a negative camber, andwhen the suspension moves in a rebound stroke, the camber angle of thesteered wheel may have a positive camber.

As a result of the camber angle being able to change between a negativecamber and a positive camber in response to the stroke of thesuspension, it is possible to reduce the amount of change in the anglebetween the longitudinal direction of each of the upper arm and thelower arm and the tire center line.

In a preferred embodiment, in a state where the vehicle is stationary onthe level road surface, the anhedral angle of the upper arm may be 15degrees or more, and the anhedral angle of the lower arm may be 20degrees or more.

As a result of the anhedral angle of the upper arm and the anhedralangle of the lower arm being as large as 15 degrees or more and 20degrees or more, respectively, it is possible to increase the rollrigidity.

In a preferred embodiment, in a state where the vehicle is stationary onthe level road surface, the anhedral angle of the upper arm may be 15degrees or more and 20 degrees or less, and the anhedral angle of thelower arm may be 20 degrees or more and 25 degrees or less.

As a result of the anhedral angle of the upper arm and the anhedralangle of the lower arm being large, it is possible to increase the rollrigidity.

In a preferred embodiment, a swing angle of each of the upper arm andthe lower arm may be 30 degrees or more.

As a result of the swing angle of the upper arm and the swing angle ofthe lower arm being as large as 30 degrees or more, it is possible toimprove the driving performance on unpaved roads and bumps.

In a preferred embodiment, the swing angle of each of the upper arm andthe lower arm may be 30 degrees or more and 60 degrees or less.

As a result of the swing angle of the upper arm and the swing angle ofthe lower arm being large, it is possible to improve the drivingperformance on unpaved roads and bumps.

In a preferred embodiment, the wheel stroke of the suspension may be 60mm or more.

As a result of the wheel stroke being as large as 60 mm or more, it ispossible to improve the driving performance on unpaved roads and bumps.

In a preferred embodiment, the wheel stroke of the suspension may be 60mm or more and 150 mm or less.

As a result of the wheel stroke being large, it is possible to improvethe driving performance on unpaved roads and bumps.

In a preferred embodiment, the wheel stroke of the suspension may be 0.5times or more of the length in the longitudinal direction of each of theupper arm and the lower arm.

As a result of the wheel stroke being as large as 0.5 times or more ofthe length in the longitudinal direction of each of the upper arm andthe lower arm, it is possible to improve the driving performance onunpaved roads and bumps.

In a preferred embodiment, the wheel stroke of the suspension may be 0.5times or more and 0.80 times or less of the length in the longitudinaldirection of each of the upper arm and the lower arm.

As a result of the wheel stroke being large, it is possible to improvethe driving performance on unpaved roads and bumps.

In a preferred embodiment, the steered wheel may include an inner wheeland an outer wheel, a maximum value of a steering angle of the innerwheel may be 50 degrees or more, and a maximum value of a steering angleof the outer wheel may be 35 degrees or more.

As a result of the steering angle of the steered wheel being large, itis possible to reduce the minimum turning radius of the vehicle, and itis possible to turn in a small radius.

In a preferred embodiment, the maximum value of the steering angle ofthe inner wheel may be 50 degrees or more and 80 degrees or less, andthe maximum value of the steering angle of the outer wheel may be 35degrees or more and 80 degrees or less.

As a result of the steering angle of the steered wheel being large, itis possible to reduce the minimum turning radius of the vehicle, and itis possible to turn in a small radius.

In a preferred embodiment, the minimum turning radius of the vehicle maybe 2.5 times or less of the tread width of the steered wheels.

As a result of the minimum turning radius for the tread width beingsmall, it is possible to turn in a small radius.

In a preferred embodiment, the minimum turning radius of the vehicle maybe 1400 mm or less.

As a result of the minimum turning radius of the vehicle being small, itis possible to turn in a small radius.

In a preferred embodiment, an outer diameter of the steered wheel may be0.26 times or more of the overall length of the vehicle.

As a result of the outer diameter of the steered wheel being as large as0.26 times or more of the overall length of the vehicle, it is possibleto improve the driving performance on unpaved roads and bumps and toimprove the ride comfort.

In a preferred embodiment, the outer diameter of the steered wheel maybe 0.26 times or more and 0.4 times or less of the overall length of thevehicle.

As a result of the outer diameter of the steered wheel being largerelative to the overall length of the vehicle, it is possible to improvethe driving performance on unpaved roads and bumps and to improve theride comfort.

In a preferred embodiment, the outer diameter of the steered wheel maybe 0.43 times or more of a wheelbase of the vehicle.

As a result of the outer diameter of the steered wheel being as large as0.43 times or more of the wheelbase of the vehicle, it is possible toimprove the driving performance on unpaved roads and bumps and toimprove the ride comfort.

In a preferred embodiment, the outer diameter of the steered wheel maybe 0.43 times or more and 0.67 times or less of a wheelbase of thevehicle.

As a result of the outer diameter of the steered wheel being largerelative to the wheelbase of the vehicle, it is possible to improve thedriving performance on unpaved roads and bumps and to improve the ridecomfort.

In a preferred embodiment, the vehicle may be an electric wheelchair,and may further include a handle that is steered by a passenger, and aseat on which the passenger is seated.

It is possible to realize an electric wheelchair, wherein the wheelstroke is large and the steering angle of the steered wheel is large.

As a result of the anhedral angle of the lower arm being larger than theanhedral angle of the upper arm, with the anhedral angle differencebeing 5 degrees or more, it is possible to reduce the amount of changein the angle between the longitudinal direction of each of the upper armand the lower arm and the tire center line when the suspension moves ina stroke. This increases the clearance between the suspension and thesteered wheel, and it is possible to both increase the wheel stroke andincrease the steering angle of the steered wheel.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a vehicle 1 according to apreferred embodiment of the present invention.

FIG. 2 is a left side view showing the vehicle 1 according to apreferred embodiment of the present invention.

FIG. 3 is a front view showing the vehicle 1 according to a preferredembodiment of the present invention.

FIG. 4A is a plan view showing an overview of a steering mechanismincluded in the vehicle 1 according to a preferred embodiment of thepresent invention.

FIG. 4B is a plan view showing an overview of the steering mechanism ofthe vehicle 1 according to a preferred embodiment of the presentinvention.

FIG. 5 is a front view showing a rear suspension 50 according to apreferred embodiment of the present invention.

FIG. 6 is a block diagram showing the electrical configuration of thevehicle 1 according to a preferred embodiment of the present invention.

FIG. 7 is a front view showing the front suspension 40 according to apreferred embodiment of the present invention.

FIG. 8 is a front view showing the front suspension 40 according to apreferred embodiment of the present invention.

FIG. 9 is a front view showing a front suspension 40 a of a comparativeexample.

FIG. 10 is a front view showing the front suspension 40 a according tothe comparative example.

FIG. 11 is a front view showing the front suspension 40 according to apreferred embodiment of the present invention.

FIG. 12 is a diagram showing the steering angles of steered wheels 4Land 4R according to a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will now be describedwith reference to the drawings. Like elements are denoted by likereference signs, and will not be described redundantly. The terms front,rear, up, down, left and right, as used in the description below, referto these directions as seen from a passenger seated in the seat of thevehicle. The left-right direction of the vehicle may be referred to asthe vehicle width direction. Note that the following preferredembodiments are illustrative, and the present invention is not limitedto the following preferred embodiments.

FIG. 1 is a perspective view showing a vehicle 1 according to apreferred embodiment. FIG. 2 is a left side view showing the vehicle 1.FIG. 3 is a front view showing the vehicle 1. In order to clearlyillustrate the structure of the vehicle 1, a portion of the body coveris omitted in the figures. The vehicle 1 is, for example, a handle-typeelectric wheelchair, but the present invention is not limited thereto.An example in which the vehicle 1 is a handle-type electric wheelchairwill be described below.

The vehicle 1 includes a vehicle body frame 2 (FIG. 2 ). The vehiclebody frame 2 includes an under frame 2 u, a rear frame 2 r, a seat frame2 s and a front frame 2 f (FIG. 3 ). The under frame 2 u extends in thefront-rear direction of the vehicle 1. The rear frame 2 r extends upwardfrom a rear portion of the under frame 2 u, and the seat frame 2 sextends rearward from an upper portion of the rear frame 2 r. The frontframe 2 f extends upward from a front portion of the under frame 2 u.

A head tube 22 (FIG. 2 ) is provided on an upper portion of the frontframe 2 f (FIG. 3 ). The head tube 22 rotatably supports a steeringcolumn 26 passing through the inside thereof. A handle 6 that is steeredby the passenger is provided on an upper end portion of the steeringcolumn 26. An accelerator operator 7 (FIG. 1 ) and a pair of left andright rearview mirrors 9 are provided on the handle 6.

A body cover 28 is provided so as to cover a portion of the vehicle bodyframe 2. A front guard 29 is provided on the body cover 28. With thefront guard 29 arranged forward of the passenger, it is possible toprovide the passenger with a sense of security when driving.

An independent front suspension 40 is provided on the front frame 2 f(FIG. 3 ). The front suspension 40 includes an upper arm 41L, a lowerarm 42L and a shock absorber 45L. One end of the upper arm 41L isrotatably supported by the front frame 2 f via a pivot 46L. The otherend of the upper arm 41L rotatably supports a knuckle arm 44L via apivot 47L. One end of the lower arm 42L is rotatably supported by thefront frame 2 f via a pivot 48L. The other end of the lower arm 42Lrotatably supports the knuckle arm 44L via a pivot 49L. The knuckle arm44L rotatably supports the front wheel 4L.

The front suspension 40 includes an upper arm 41R, a lower arm 42R and ashock absorber 45R. One end of the upper arm 41R is rotatably supportedby the front frame 2 f via a pivot 46R. The other end of the upper arm41R rotatably supports a knuckle arm 44R via a pivot 47R. One end of thelower arm 42R is rotatably supported by the front frame 2 f via a pivot48R. The other end of the lower arm 42R rotatably supports the knucklearm 44R via a pivot 49R. The knuckle arm 44R rotatably supports thefront wheel 4R. The front suspension 40 rotatably supports the frontwheels 4L and 4R via the knuckle arms 44L and 44R. The front wheels 4Land 4R are steered wheels.

The front suspension 40 may be referred to as a double wishbone-typesuspension. In the present specification, the arm shape of the doublewishbone-type suspension is not limited to the A-letter shape (V-lettershape). In the present specification, “double wishbone-type” is ageneric term for a suspension system in which the wheels are supportedby a pair of upper and lower arms.

The front frame 2F is provided with a suspension tower 27. The upperportions of the shock absorbers 45L and 45R are rotatably supported bythe suspension tower 27. The lower portion of the shock absorber 45Lrotatably supports the upper arm 41L. The lower portion of the shockabsorber 45R rotatably supports the upper arm 41R.

The front frame 2 f extends in the up-down direction at a position inthe vicinity of the center in the vehicle width direction. The frameportion to which the suspension is attached is required to have highstrength because the impact received by the suspension from the roadsurface is transmitted thereto. Where the suspension tower 27 isprovided in the vicinity of the left and right end portions of thevehicle body, high strength needs to be provided in the frame portionextending in the left-right direction from the central portion in thevehicle width direction, thus resulting in a large vehicle body weight.By providing the suspension tower 27 on the front frame 2 f located inthe vicinity of the center in the vehicle width direction, there is nolonger a need for such a frame portion having high strength andextending in the left-right direction, thus realizing a reduced vehiclebody weight.

The shock absorbers 45L and 45R are attached to the upper arms 41L and41R.

FIGS. 4A and 4B are plan views showing an overview of the steeringmechanism of the vehicle 1. A pitman arm 49 is attached to the lower endportion of the steering column 26. One end of a tie rod 43L and one endof a tie rod 43R are each rotatably connected to the pitman arm 49. Theother end of the tie rod 43L is rotatably connected to the knuckle arm44L. The other end of the tie rod 43R is rotatably connected to theknuckle arm 44R.

FIG. 4A shows the steering mechanism when traveling straight. Whentraveling through a curve, the passenger turns the handle 6 (FIG. 1 ).Referring to FIG. 4B, the steering force generated by the passengerturning the handle 6 is transmitted to the pitman arm 49 via thesteering column 26. The pitman arm 49 rotates around the steering column26 and the steering force is transmitted to the front wheels 4L and 4Rvia the tie rods 43L and 43R and the knuckle arms 44L and 44R. Thetransmitted steering force changes the steering angle of the frontwheels 4L and 4R allowing the vehicle 1 to travel while turning left orright.

Referring to FIG. 1 and FIG. 2 , a seat 3, on which the passenger isseated, is provided on the seat frame 2 s. The seat 3 includes a seatbase 31 provided on the seat frame 2 s and a cushion 32 provided on theseat base 31.

The seat base 31 is also called a plate member or a bottom plate. Theseat base 31 forms the bottom portion of the seat 3 and serves toprovide the strength of the seat 3 as a whole. Therefore, the sheet base31 is formed from a relatively rigid material. The material of the sheetbase 31 can be, for example, but not limited to, a metal material or asynthetic resin material such as polypropylene.

The cushion 32 is overlaid on the surface of the seat base 31. Thecushion 32 can be formed from a material that retains appropriateelasticity over time to maintain good ride comfort. For example, but notlimited to, polyurethane foam (urethane foam) can be used as thematerial for the cushion 32.

On both sides of the seat 3, armrests 38 are provided on which thepassenger places his/her arms. The armrests 38 also serve as sideguards. At the rear portion of the seat 3, a backrest 39 is provided onwhich the passenger leans.

The under frame 2 u is provided with a footboard 8 (FIG. 1 ) on whichthe passenger places his/her feet. The footboard 8 has a non-slipfinish. The upper surface of the footboard 8 has a generally flat shapeso that the passenger can easily get in and out of the vehicle.

An independent rear suspension 50 (FIG. 2 ) is provided at the rearportion of the under frame 2 u. FIG. 5 is a front view showing the rearsuspension 50. The rear suspension 50 may be referred to as a trailingarm suspension.

The rear suspension 50 includes rear arms 51L and 51R and shockabsorbers 55L and 55R. The rear arms 51L and 51R are swing arms. Thefront portion of the rear arm 51L is rotatably supported on the leftrear portion of the under frame 2 u via a pivot 56L. The front portionof the rear arm 51R is rotatably supported on the right rear portion ofthe under frame 2 u via a pivot 56R.

The upper portion of the shock absorber 55L and the upper portion of theshock absorber 55R are each rotatably supported by the rear frame 2 r(FIG. 2 ). The lower portion of the shock absorber 55L rotatablysupports the rear arm 51L. The lower portion of the shock absorber 55Rrotatably supports the rear arm 51R.

An electric motor 60L is provided at the rear portion of the rear arm51L. The electric motor 60L is an in-wheel motor, and the rear wheel 5Lis provided on the electric motor 60L. The rear suspension 50 rotatablysupports the rear wheel 5L via the electric motor 60L. The electricmotor 60R is provided at the rear portion of the rear arm 51R. Theelectric motor 60R is an in-wheel motor, and the rear wheel 5R isprovided on the electric motor 60R. The rear suspension 50 rotatablysupports the rear wheel 5R via the electric motor 60R. The rear wheels5L and 5R are drive wheels.

The vehicle 1 of the present preferred embodiment employs large-sizedwheels 4L, 4R, 5L and 5R. The outer diameters of the front wheels andthe rear wheels are, for example, but not limited to, 14 inches or more.By employing larger-sized front wheels and rear wheels, it is possibleto improve the driving performance on unpaved roads and bumps.

In the present preferred embodiment, two electric motors 60L and 60R areused to drive the rear wheels 5L and 5R independently of each other. Bycontrolling the rotation of the left wheels and that of the right wheelsindependently, it is possible to enhance the stability of the behaviorof the vehicle 1 when turning. With vehicles that have differentialgears, when one drive wheel idles, it is difficult for the driving forceto be transmitted to the other drive wheel. In the present preferredembodiment, even if one of the rear wheels 5L and 5R idles, the othercan provide grip so as to continue driving stably.

Note that the electric motors driving the rear wheels 5L and 5R are notlimited to in-wheel motors. For example, a single electric motor maytransmit driving power to the rear wheels 5L and 5R.

Although a two-wheel drive configuration is illustrated here in whichthe electric motors 60L and 60R drive the rear wheels 5L and 5R, thevehicle 1 may be four-wheel drive. In that case, in-wheel motors arealso provided for each of the front wheels 4L and 4R. Note that thedriving force may be transmitted from one electric motor to the frontwheels 4L and 4R. The driving force may be transmitted from one electricmotor to each of the front wheels 4L and 4R and the rear wheels 5L and5R.

The vehicle 1 of the present preferred embodiment includes theindependent front suspension 40 and the independent rear suspension 50.Two electric motors 60L and 60R are used to drive the rear wheels 5L and5R independently of each other. Thus, it is possible to improve theability to follow road surface irregularities and stably transmitdriving force to the road surface. It is also possible to improve theturning performance of the vehicle. According to the present preferredembodiment, it is possible to improve the vehicle's driving performanceon unpaved roads and bumps.

Note that the rear suspension 50 is not limited to an independentsuspension, but may be an axle suspension.

The present preferred embodiment employs in-wheel motors as the electricmotor. This eliminates the need to provide space for arranging theelectric motor and the power transmission mechanism in the body portionof the vehicle, thus saving space. Since a drive shaft extending in theleft-right direction of the vehicle 1 is not required, the rearsuspension 50 is not restricted by the drive shaft. In the rearsuspension 50, the rear arms 51L and 51R extend in the front-reardirection and the pivots 56L and 56R are located forward relative to arotation shaft 57 of the rear wheel 5L and 5R. With such aconfiguration, it is possible to increase the wheel stroke of the rearsuspension 50.

The wheel stroke of the rear suspension 50 is, for example, but notlimited to, 60 mm or more. As the wheel stroke is as large as 60 mm ormore, it is possible to improve the driving performance on unpaved roadsand bumps. The upper limit of the wheel stroke of the rear suspension 50may vary depending on the size of the vehicle 1, and is for example, butnot limited to, 150 mm.

Since the drive shaft is not needed and the rear arms 52L and 51R arenot located near the central portion of the rear of the vehicle, it ispossible to provide space near the central portion of the rear of thevehicle. The space near the central portion of the rear of the vehiclemakes it difficult for the main body portion of the vehicle to come intocontact with the ground even when a large difference in position in theup-down direction occurs between the left and right rear wheels 5L and5R in response to the operation of the independent rear suspension 50.Note that if the drive power is transmitted to the rear wheels 5L and 5Rfrom a single electric motor instead of using in-wheel motors, thevehicle 1 may include a drive shaft.

Next, the control of the electric motors 60L and 60R will be described.FIG. 6 is a block diagram showing the electrical configuration of thevehicle 1. The vehicle 1 includes a control device 70. The controldevice 70 controls the operation of the vehicle 1. The control device 70includes, for example, a Motor Control Unit (MCU). Typically, thecontrol device 70 includes a semiconductor integrated circuit, such as amicrocontroller, a signal processor, etc., capable of performing digitalsignal processing.

The control device 70 includes a processor 71, a memory 72 and drivecircuits 73L and 73R. The processor 71 controls the operation of theelectric motors 60L and 60R and the operation of the various parts ofthe vehicle 1. The memory 72 stores a computer program that definesprocedures for controlling the operation of the electric motors 60L and60R and the various parts of the vehicle 1. The processor 71 reads thecomputer program from the memory 72 and performs various controls. Thecontrol device 70 is supplied with electric power from the battery 10.The control device 70 and the battery 10 can be installed at anyposition of the vehicle 1, for example, but not limited to, downward ofthe seat 3. The battery 10 can be provided so as to be removable fromthe vehicle 1. For example, the battery 10 may be attached/removedto/from the rear of the seat 3. By arranging the battery 10 at an endportion of the vehicle around the seat 3, the passenger can easilyattach/remove the battery 10.

The accelerator operator 7 outputs to the processor 71 a signal inaccordance with the amount by which the accelerator is operated by thepassenger. The steering angle sensor 75 is provided on the head tube 22or the steering column 26, for example, and outputs a signal to theprocessor 71 in accordance with the angle of rotation of the steeringcolumn 26.

The electric motor 60L is provided with a rotation sensor 61L. Therotation sensor 61L detects the rotation angle of the electric motor 60Land outputs a signal in accordance with the rotation angle to theprocessor 71 and the drive circuit 73L. The processor 71 and the drivecircuit 73L calculate the rotation speed of the electric motor 60L fromthe output signal of the rotation sensor 61L.

The electric motor 60R is provided with a rotation sensor 61R. Therotation sensor 61R detects the rotation angle of the electric motor 60Rand outputs a signal in accordance with the rotation angle to theprocessor 71 and the drive circuit 73R. The processor 71 and the drivecircuit 73R calculate the rotation speed of the electric motor 60R fromthe output signal of the rotation sensor 61R. The sizes of the rearwheels 5L and 5R are stored in the memory 72 in advance, and the drivingspeed of the vehicle 1 can be calculated from the rotation speed of theelectric motors 60L and 60R.

The processor 71 calculates, and transmits to the drive circuits 73L and73R, a command value for generating an appropriate driving force fromthe output signal of the accelerator operator 7, the output signal ofthe steering angle sensor 75, the traveling speed of the vehicle, andinformation stored in the memory 72, etc. The processor 71 can senddifferent command values to the drive circuits 73L and 73R depending onthe driving condition of the vehicle.

The drive circuits 73L and 73R include, for example, inverters. Thedrive circuit 73L supplies a drive current in accordance with thecommand value from the processor 71 to the electric motor 60L. The drivecircuit 73R supplies the drive current in accordance with the commandvalue from the processor 71 to the electric motor 60L. The electricmotors 60L and 60R to which the drive current is supplied rotate, thuscausing the rear wheels 5L and 5R to rotate. If the electric motors 60Land 60R include decelerators, the rotation is transmitted to the rearwheels 5L and 5R via those decelerators.

As described above, the vehicle 1 of the present preferred embodimentincludes wheels 4L, 4R, 5L and 5R with a larger outer diameter. Thus, itis possible to improve the running performance on unpaved roads andbumps. On the other hand, the overall length (length in the front-reardirection) of the vehicle 1 may be limited. For example, the JapaneseIndustrial Standards “JIS T 9208:2016” for handle-type electricwheelchairs limits the overall length of the vehicle to 1200 mm or less.Thus, where the overall length of the vehicle 1 is limited, thewheelbase will be shorter if the outer diameter of the wheels isincreased.

Referring to FIG. 2 , the outer diameters Dw of the wheels 4L, 4R, 5Land 5R of the present preferred embodiment are relatively large, forexample, more than 0.26 times the overall length Lo of the vehicle 1.The outer diameter Dw of the wheels is relatively large, for example,more than 0.43 times the wheelbase WB of the vehicle 1. Thus, if thesize of the wheel is relatively large, it is difficult to increase thesteering angle of the wheel. The upper limit of the outer diameter Dw ofthe wheel is, for example, but not limited to, 0.4 times the overalllength Lo of the vehicle 1. The wheel outer diameter Dw is, for example,but not limited to, at most 0.67 times the wheelbase WB.

When a wheel with a large outer diameter and width is used as a steeredwheel, the suspension supporting the steered wheel and the steered wheelare more likely to interfere with each other, making it difficult toincrease the steering angle of the steered wheel. However, vehicles suchas handle-type electric wheelchairs are required to be able to turn in asmall radius, and the steering angle of the steered wheels is requiredto be large. When wheels with a large outer diameter and width are used,it is easy for the wheels to interfere with the suspension when thewheels stroke in the up-down direction, thus making it difficult toincrease the wheel stroke.

The front suspension 40 of the present preferred embodiment, with whichit is possible to increase the steering angle and the wheel stroke, willnow be described in detail.

Referring to FIG. 3 , the angles of the upper arms 41L and 41R and thelower arms 42L and 42R will be described.

FIG. 3 shows the vehicle 1 in a predetermined state, stationary on alevel road surface 15 with a weight having a mass of 75 kg on the seat 3(FIG. 1 ). The weight is one of the weights specified in the JapaneseIndustrial Standards “JIS T 9208:2016” for handle-type electricwheelchairs. With such a weight on the seat 3, it is possible tosimulate the state where a human rides in the vehicle 1.

As shown in FIG. 3 , the upper arm 41L and the lower arm 42L of thefront suspension 40 are inclined so that the height gradually decreasesfrom the central portion in the vehicle width direction (the left-rightdirection) to the left. That is, the upper arm 41L and the lower arm 42Lhave anhedral angles θ_(41L) and θ_(42L). The anhedral angle is theangle between the vehicle width direction and the longitudinal directionof the arm as the front suspension 40 is viewed from front. When thevehicle 1 is stationary on the level road surface 15, the vehicle widthdirection can be parallel to the horizontal direction. The longitudinaldirection of the arm is, for example, the direction extending from thecenter of the pivot on the front frame 2 f side toward the center of thepivot on the knuckle arm side. The anhedral angle may be referred to asa negative dihedral angle.

The upper arm 41R and the lower arm 42R of the front suspension 40 areinclined so that the height gradually decreases from the central portionin the vehicle width direction toward the right side. That is, the upperarm 41R and the lower arm 42R have anhedral angles θ_(41R) and θ_(42R).

The anhedral angles θ_(41L) and θ_(41R) of the upper arms 41L and 41Rare 15 degrees or more, for example. The anhedral angles θ_(42L) andθ_(42R) of the lower arms 42L and 42R are 20 degrees or more, forexample. With the large anhedral angles of the arms, it is possible toincrease the roll rigidity of the vehicle 1. The upper limit of theanhedral angles θ_(41L) and θ_(41R) of the upper arms 41L and 41R is,for example, but not limited to, 20 degrees. The upper limit of theanhedral angle θ_(42L) and θ_(42R) of the lower arms 42L and 42R is, forexample, but not limited to, 25 degrees. Needless to say, each arm ofthe front suspension 40 has an anhedral angle even when theabove-mentioned weight is absent on the seat 3 (corresponding to a statewhere no passenger is on board).

In the present preferred embodiment, the anhedral angle θ_(42L) of thelower arm 42L is greater than the anhedral angle θ_(41L) of the upperarm 41L. The difference between the anhedral angle θ_(42L) of the lowerarm 42L and the anhedral angle θ_(41L) of the upper arm 41L is, forexample, 5 degrees or more. The anhedral angle θ_(42R) of the lower arm42R is greater than the anhedral angle θ_(41R) of the upper arm 41R. Thedifference between the anhedral angle θ_(42R) of the lower arm 42R andthe anhedral angle θ_(41R) of the upper arm 41R is, for example, 5degrees or more. By setting the difference between the anhedral angle ofthe lower arm and the anhedral angle of the upper arm to 5 degrees ormore, it is possible to obtain a desired amount of change in the camberangle as will be described below. The upper limit of the differencebetween the anhedral angle of the lower arm and the anhedral angle ofthe upper arm is, for example, but not limited to, 9 degrees. Forexample, the upper limit of the anhedral angle difference may be 8degrees.

FIG. 7 and FIG. 8 are front views showing the front suspension 40. Thefeatures of the upper arm 41L, the lower arm 42L, the knuckle arm 44Land the front wheel 4L will now be described primarily, but the featuresof the upper arm 41R, the lower arm 42R, the knuckle arm 44R and thefront wheel 4R are the same. Since the steered wheels in the presentpreferred embodiment are the front wheels, the front wheels may bereferred to as the steered wheels.

FIG. 7 shows the front suspension 40 when the steered wheel 4L moves inthe upward direction, i.e., when the front suspension 40 is retracted.FIG. 8 shows the front suspension 40 when the steered wheel 4L moves inthe downward direction, i.e., when the front suspension 40 is extended.

The present inventors have discovered that by making the anhedral angleθ_(42L) of the lower arm 42L (FIG. 3 ) larger than the anhedral angleθ_(41L) of the upper arm 41L, it is possible to increase the amount ofchange in the camber angle θc of the steered wheel 4L when the frontsuspension 40 strokes. For example, the amount of change in the camberangle θc with respect to the wheel stroke can be set to 5 degrees ormore.

As the camber angle θc changes significantly in response to the strokeof the front suspension 40, it is possible to reduce the amount ofchange in the angle Cu between the longitudinal direction LD1 of theupper arm 41L and the tire center line CtL when the front suspension 40strokes. It is possible to reduce the amount of change in the angle θ1between the longitudinal direction LD2 of the lower arm 42L and the tirecenter line CtL when the front suspension 40 strokes.

The amount of change in the angle between the longitudinal direction ofthe arm and the tire center line means that there is little change inthe positional relationship between the arm and the steered wheel. Thus,it is possible to increase the clearance between the front suspension 40and the steered wheel 4L. As the clearance is large, it is possible toincrease the steering angle of the steered wheel 4L and also to increasethe wheel stroke.

FIG. 9 and FIG. 10 are front views showing, as a comparative example, afront suspension 40 a where the anhedral angle θ_(42L) of the lower arm42L (FIG. 3 ) and the anhedral angle θ_(41L) of the upper arm 41L areequal to each other. In the front suspension 40 a, the longitudinaldirection LD1 of the upper arm 41L is parallel to the longitudinaldirection LD2 of the lower arm 42L. FIG. 9 shows the front suspension 40a when the steered wheel 4L moves in the upward direction. FIG. 10 showsthe front suspension 40 a when the steered wheel 4L moves in thedownward direction.

When the front suspension 40 a moves in a stroke, the camber angle doesnot substantially change. Therefore, the amount of change in the angleCu between the longitudinal direction LD1 of the upper arm 41L and thetire center line CtL when moving in a stroke is large. Similarly, theamount of change in the angle θ1 between the longitudinal direction LD2of the lower arm 42L and the tire center line CtL when moving in astroke is large.

The amount of change in the angle between the longitudinal direction ofthe arm and the tire center line being large means that the change inthe positional relationship between the arm and the steered wheel islarge. As the positional relationship between the arm and the steeredwheel changes significantly, it is difficult to provide clearance.

On the other hand, as described above, with the front suspension 40 ofthe present preferred embodiment, the change in the positionalrelationship between the arm and the steered wheel is small. Thus, it ispossible to increase the clearance between the front suspension 40 andthe steered wheel 4L, and it is possible to increase the steering angleof the steered wheel 4L and to increase the wheel stroke.

In the present preferred embodiment, when the front suspension 40 makesa bound stroke, the camber angle θc of the steered wheel 4L can have anegative camber. When the front suspension 40 makes a rebound stroke,the camber angle θc of the steered wheel 4L can have a positive camber.By varying the camber angle θc between the negative camber and thepositive camber in response to the stroke of the front suspension 40, itis possible to reduce the amount of change in the angle between thelongitudinal direction of the arm and the tire center line.

Note that the upper limit of the amount of change in the camber angle θcwith respect to wheel stroke is, for example, but not limited to, 10degrees.

FIG. 11 is a front view showing the front suspension 40 of the presentpreferred embodiment. FIG. 11 shows the front suspension 40 in the boundstroke state is indicated by a solid line, and the front suspension 40in the rebound stroke state is indicated by a dotted line.

In the present preferred embodiment, since it is possible to increasethe clearance between the front suspension 40 and the steered wheel 4L,it is possible to increase the arm swing angle and the wheel stroke.

The swing angle θs1 of the upper arm 41L and the swing angle θs2 of thelower arm 42L are each 30 degrees or more, for example. With the largeswing angle of 30 degrees or more, it is possible to improve the drivingperformance on unpaved roads and bumps. The wheel stroke WS is, forexample, 60 mm or more. With the large wheel stroke WS of 60 mm or more,it is possible to improve the driving performance on unpaved roads andbumps.

The wheel stroke WS is 0.5 times or more of the length D₄₁ (FIG. 7 ) inthe longitudinal direction of the upper arm 41L and 0.5 times or more ofthe length D₄₂ in the longitudinal direction of the lower arm 42L. Thelength in the longitudinal direction of the arm is, for example, thelength between the center of the pivot on the front frame 2F side andthe center of the pivot on the knuckle arm side. As the wheel stroke WSis large relative to the length of the arm, it is possible to improvethe driving performance on unpaved roads and bumps.

The upper limit of the swing angles θs1 and θs2 is, for example, but notlimited to, 60 degrees. The upper limit of the wheel stroke WS is, forexample, but not limited to, 150 mm. The wheel stroke WS is, forexample, but not limited to, at maximum 0.80 times the length in thelongitudinal direction of the arm.

Next, the steering angle of the steered wheels 4L and 4R will bedescribed. FIG. 12 are views showing the steering angle of the steeredwheels 4L and 4R. The reference signs CtL and CtR in FIG. 12 representthe tire center lines of the steered wheels 4L and 4R. FIG. 12 shows thesteering angle when the vehicle 1 is turning right. In the presentpreferred embodiment, since it is possible to increase the clearancebetween the front suspension 40 and the steered wheel 4L, it is possibleto increase the steering angle of the steered wheels 4L and 4R.

When the vehicle 1 turns right, the steered wheel 4R is the inner wheeland the steered wheel 4L is the outer wheel. In the present preferredembodiment, the maximum value of the steering angle of the inner wheelis, for example, 50 degrees or more, and the maximum value of thesteering angle of the outer wheel is, for example, 35 degrees or more.

In this example, the steering angle of the inner wheel is larger thanthe steering angle of the outer wheel. Such a relationship in thesteering angle between the inner wheel and the outer wheel can beachieved, for example, by employing Ackermann-type steering. It may alsobe realized, for example, by a steering system in which the steeringangle of the inner wheel and the steering angle of the outer wheel arecontrolled independently of each other.

As described above, with the steering angles of the steered wheels 4Land 4R are large, it is possible to reduce the minimum turning radius ofthe vehicle 1, and it is possible to turn in a small radius. The maximumvalue of the steering angle of the inner wheel is, for example, but notlimited to, 80 degrees or less. The maximum value of the steering angleof the outer wheel is, for example, but not limited to, 80 degrees orless.

As described above, in the present preferred embodiment, it is possibleto reduce the minimum turning radius of the vehicle 1. For example, theminimum turning radius of the vehicle 1 can be as small as 2.5 times orless of the tread width TW of the steered wheels 4L and 4R. The minimumturning radius of the vehicle 1 is, for example, 1400 mm or less. As theminimum turning radius of the vehicle 1 is small, it is possible to turnin a small radius.

While the vehicle 1 is a four-wheeled handle-type electric wheelchair inthe description of a preferred embodiment above, the vehicle 1 is notlimited thereto. The vehicle 1 may be a joystick-type electricwheelchair. The vehicle 1 is not limited to a wheelchair, but may beanother vehicle.

The number of wheels of the vehicle 1 is not limited to four wheels. Thenumber of wheels may be three or more. The drive source to drive thewheels is not limited to an electric motor, but may be an internalcombustion engine. The driving force may be transmitted from one drivesource to multiple wheels.

Illustrative preferred embodiments of the present invention have beendescribed above.

The vehicle 1 according to a preferred embodiment of the presentinvention includes at least three wheels including a steered wheel 4L,4R; at least one drive source 60L, 60R to drive at least two of thewheels; and a front suspension 40 having an upper arm 41L, 41R and alower arm 42L, 42R supporting the steered wheel 4L, 4R, wherein, in astate where the vehicle 1 is stationary on a level road surface 15, ananhedral angle of the lower arm 42L, 42R is larger than an anhedralangle of the upper arm 41L, 41R; and a difference between the anhedralangle of the lower arm 42L, 42R and the anhedral angle of the upper arm41L, 41R is 5 degrees or more.

As the anhedral angle of the lower arm 42L, 42R is larger than theanhedral angle of the upper arm 41L, 41R, with the anhedral angledifference being 5 degrees or more, it is possible to reduce the amountof change in the angle between the longitudinal direction of each of theupper arm 41L, 41R and the lower arm 42L, 42R and the tire center linewhen the front suspension 40 moves in a stroke. This increases theclearance between the front suspension 40 and the steered wheel 4L, 4R,and it is possible to both increase the wheel stroke WS and increase thesteering angle of the steered wheel 4L, 4R.

In a preferred embodiment, the difference between the anhedral angle ofthe lower arm 42L, 42R and the anhedral angle of the upper arm 41L, 41Rmay be 5 degrees or more and 9 degrees or less.

As the difference between the anhedral angle of the lower arm 42L, 42Rand the anhedral angle of the upper arm 41L, 41R is large, it ispossible to reduce the amount of change in the angle between thelongitudinal direction of each of the upper arm 41L, 41R and the lowerarm 42L, 42R and the tire center line when the suspension 40 moves in astroke.

In a preferred embodiment, the amount of change in a camber angle of thesteered wheel 4L, 4R relative to the wheel stroke WS of the frontsuspension 40 may be 5 degrees or more.

As the camber angle of the steered wheel 4L, 4R significantly changes inresponse to the stroke of the front suspension 40, it is possible toreduce the amount of change in the angle between the longitudinaldirection of each of the upper arm 41L, 41R and the lower arm 42L, 42Rand the tire center line.

In a preferred embodiment, the amount of change in the camber angle ofthe steered wheel 4L, 4R relative to the wheel stroke WS of the frontsuspension 40 may be 5 degrees or more and 10 degrees or less.

As the camber angle of the steered wheel 4L, 4R significantly changes inresponse to the stroke of the front suspension 40, it is possible toreduce the amount of change in the angle between the longitudinaldirection of each of the upper arm 41L, 41R and the lower arm 42L, 42Rand the tire center line.

In a preferred embodiment, when the front suspension 40 moves in a boundstroke, the camber angle of the steered wheel 4L, 4R may have a negativecamber; and when the front suspension 40 moves in a rebound stroke, thecamber angle of the steered wheel 4L, 4R may have a positive camber.

As the camber angle changes between a negative camber and a positivecamber in response to the stroke of the front suspension 40, it ispossible to reduce the amount of change in the angle between thelongitudinal direction of each of the upper arm 41L, 41R and the lowerarm 42L, 42R and the tire center line.

In a preferred embodiment, in a state where the vehicle 1 is stationaryon the level road surface 15, the anhedral angle of the upper arm 41L,41R may be 15 degrees or more, and the anhedral angle of the lower arm42L, 42R may be 20 degrees or more.

As the anhedral angle of the upper arm 41L, 41R and the anhedral angleof the lower arm 42L, 42R are as large as 15 degrees or more and 20degrees or more, respectively, it is possible to increase the rollrigidity.

In a preferred embodiment, in a state where the vehicle 1 is stationaryon the level road surface 15, the anhedral angle of the upper arm 41L,41R may be 15 degrees or more and 20 degrees or less, and the anhedralangle of the lower arm 42L, 42R may be 20 degrees or more and 25 degreesor less.

As the anhedral angle of the upper arm 41L, 41R and the anhedral angleof the lower arm 42L, 42R are large, it is possible to increase the rollrigidity.

In a preferred embodiment, a swing angle of each of the upper arm 41L,41R and the lower arm 42L, 42R may be 30 degrees or more.

As the swing angle of the upper arm 41L, 41R and the swing angle of thelower arm 42L, 42R are as large as 30 degrees or more, it is possible toimprove the driving performance on unpaved roads and bumps.

In a preferred embodiment, the swing angle of each of the upper arm 41L,41R and the lower arm 42L, 42R may be 30 degrees or more and 60 degreesor less.

As the swing angle of the upper arm 41L, 41R and the swing angle of thelower arm 42L, 42R are large, it is possible to improve the drivingperformance on unpaved roads and bumps.

In a preferred embodiment, the wheel stroke WS of the front suspension40 may be 60 mm or more.

As the wheel stroke WS is as large as 60 mm or more, it is possible toimprove the driving performance on unpaved roads and bumps.

In a preferred embodiment, the wheel stroke WS of the front suspension40 may be 60 mm or more and 150 mm or less.

As the wheel stroke WS is large, it is possible to improve the drivingperformance on unpaved roads and bumps.

In a preferred embodiment, the wheel stroke WS of the front suspension40 may be 0.5 times or more of the length in the longitudinal directionof each of the upper arm 41L, 41R and the lower arm 42L, 42R.

As the wheel stroke WS is as large as 0.5 times or more of the length inthe longitudinal direction of each of the upper arm 41L, 41R and thelower arm 42L, 42R, it is possible to improve the driving performance onunpaved roads and bumps.

In a preferred embodiment, the wheel stroke WS of the front suspension40 may be 0.5 times or more and 0.80 times or less of the length in thelongitudinal direction of each of the upper arm 41L, 41R and the lowerarm 42L, 42R.

As the wheel stroke WS is large, it is possible to improve the drivingperformance on unpaved roads and bumps.

In a preferred embodiment, the steered wheel 4L, 4R may include an innerwheel and an outer wheel, a maximum value of a steering angle of theinner wheel may be 50 degrees or more, and a maximum value of a steeringangle of the outer wheel may be 35 degrees or more.

As the steering angle of the steered wheel 4L, 4R is large, it ispossible to reduce the minimum turning radius of the vehicle 1, and itis possible to turn in a small radius.

In a preferred embodiment, the maximum value of the steering angle ofthe inner wheel may be 50 degrees or more and 80 degrees or less, andthe maximum value of the steering angle of the outer wheel may be 35degrees or more and 80 degrees or less.

As the steering angle of the steered wheel 4L, 4R is large, it ispossible to reduce the minimum turning radius of the vehicle 1, and itis possible to turn in a small radius.

In a preferred embodiment, the minimum turning radius of the vehicle 1may be 2.5 times or less of the tread width of the steered wheels 4L,4R.

As the minimum turning radius for the tread width is small, it ispossible to turn in a small radius.

In a preferred embodiment, the minimum turning radius of the vehicle 1may be 1400 mm or less.

As the minimum turning radius of the vehicle 1 is small, it is possibleto turn in a small radius.

In a preferred embodiment, an outer diameter Dw of the steered wheel 4L,4R may be 0.26 times or more of an overall length Lo of the vehicle 1.

As the outer diameter Dw of the steered wheel 4L, 4R is as large as 0.26times or more of the overall length Lo of the vehicle 1, it is possibleto improve the driving performance on unpaved roads and bumps and toimprove the ride comfort.

In a preferred embodiment, the outer diameter Dw of the steered wheel4L, 4R may be 0.26 times or more and 0.4 times or less of the overalllength Lo of the vehicle 1.

As the outer diameter Dw of the steered wheel 4L, 4R is large relativeto the overall length Lo of the vehicle 1, it is possible to improve thedriving performance on unpaved roads and bumps and to improve the ridecomfort.

In a preferred embodiment, the outer diameter Dw of the steered wheel4L, 4R may be 0.43 times or more of a wheelbase of the vehicle 1.

As the outer diameter Dw of the steered wheel 4L, 4R is as large as 0.43times or more of the wheelbase of the vehicle 1, it is possible toimprove the driving performance on unpaved roads and bumps and toimprove the ride comfort.

In a preferred embodiment, the outer diameter Dw of the steered wheel4L, 4R may be 0.43 times or more and 0.67 times or less of a wheelbaseof the vehicle 1.

As the outer diameter Dw of the steered wheel 4L, 4R is large relativeto the wheelbase of the vehicle 1, it is possible to improve the drivingperformance on unpaved roads and bumps and to improve the ride comfort.

In a preferred embodiment, the vehicle 1 may be a handle-type electricwheelchair, and may further include a handle 6 that is steered by apassenger, and a seat 3 on which the passenger is seated.

It is possible to realize a handle-type electric wheelchair, wherein thewheel stroke WS is large and the steering angle of the steered wheel 4L,4R is large.

Preferred embodiments of the present invention are particularly usefulin the field of vehicles.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A vehicle comprising: at least three wheelsincluding a steered wheel; at least one drive source to drive at leasttwo of the wheels; and a suspension including an upper arm and a lowerarm supporting the steered wheel; wherein in a state where the vehicleis stationary on a level road surface, an anhedral angle of the lowerarm is larger than an anhedral angle of the upper arm, and a differencebetween the anhedral angle of the lower arm and the anhedral angle ofthe upper arm is 5 degrees or more.
 2. The vehicle according to claim 1,wherein the difference between the anhedral angle of the lower arm andthe anhedral angle of the upper arm is 5 degrees or more and 9 degreesor less.
 3. The vehicle according to claim 1, wherein an amount ofchange in a camber angle of the steered wheel relative to a wheel strokeof the suspension is 5 degrees or more.
 4. The vehicle according toclaim 3, wherein the amount of change in the camber angle of the steeredwheel relative to the wheel stroke of the suspension is 5 degrees ormore and 10 degrees or less.
 5. The vehicle according to claim 1,wherein when the suspension moves in a bound stroke, the camber angle ofthe steered wheel has a negative camber; and when the suspension movesin a rebound stroke, the camber angle of the steered wheel has apositive camber.
 6. The vehicle according to claim 1, wherein, in astate where the vehicle is stationary on a level road surface, theanhedral angle of the upper arm is 15 degrees or more, and the anhedralangle of the lower arm is 20 degrees or more.
 7. The vehicle accordingto claim 6, wherein, in a state where the vehicle is stationary on alevel road surface, the anhedral angle of the upper arm is 15 degrees ormore and 20 degrees or less, and the anhedral angle of the lower arm is20 degrees or more and 25 degrees or less.
 8. The vehicle according toclaim 1, wherein a swing angle of the upper arm and a swing angle of thelower arm are each 30 degrees or more.
 9. The vehicle according to claim8, wherein the swing angle of the upper arm and the swing angle of thelower arm are each 30 degrees or more and 60 degrees or less.
 10. Thevehicle according to claim 1, wherein a wheel stroke of the suspensionis 60 mm or more.
 11. The vehicle according to claim 10, wherein thewheel stroke of the suspension is 60 mm or more and 150 mm or less. 12.The vehicle according to claim 1, wherein a wheel stroke of thesuspension is 0.5 times or more of a length in a longitudinal directionof each of the upper arm and the lower arm.
 13. The vehicle according toclaim 12, wherein the wheel stroke of the suspension is 0.5 times ormore and 0.8 times or less of a length in the longitudinal direction ofeach of the upper arm and the lower arm.
 14. The vehicle according toclaim 1, wherein the steered wheel includes an inner wheel and an outerwheel; a maximum value of a steering angle of the inner wheel is 50degrees or more; and a maximum value of a steering angle of the outerwheel is 35 degrees or more.
 15. The vehicle according to claim 14,wherein the maximum value of the steering angle of the inner wheel is 50degrees or more and 80 degrees or less; and the maximum value of thesteering angle of the outer wheel is 35 degrees or more and 80 degreesor less.
 16. The vehicle according to claim 1, wherein a minimum turningradius of the vehicle is 2.5 times or less of a tread width of thesteered wheel.
 17. The vehicle according to claim 1, wherein a minimumturning radius of the vehicle is 1400 mm or less.
 18. The vehicleaccording to claim 1, wherein an outer diameter of the steered wheel is0.26 times or more of a total length of the vehicle.
 19. The vehicleaccording to claim 18, wherein an outer diameter of the steered wheel is0.26 times or more and 0.4 times or less of an overall length of thevehicle.
 20. The vehicle according to claim 1, wherein an outer diameterof the steered wheel is 0.43 times or more of a wheelbase of thevehicle.
 21. The vehicle according to claim 1, wherein an outer diameterof the steered wheel is 0.43 times or more and 0.67 times or less of awheelbase of the vehicle.
 22. The vehicle according to claim 1, whereinthe vehicle is an electric wheelchair including a handle to be steeredby a passenger; and the vehicle further includes a seat on which thepassenger is to be seated.